- var_dump: documentation ( source)
<?php
$dt = new \DateTime('2018-04-01 03:10:00', new \DateTimeZone('Pacific/Auckland'));
$dt2 = clone $dt;
$dt2->sub(new \DateInterval('PT2H'));
var_dump($dt > $dt2, $dt->format(\DateTime::RFC3339), $dt2->format(\DateTime::RFC3339), $dt->diff($dt2)->format('%h'));